Ghost Underseat Subwoofers

[Ian-Ross]

Guys, I think I just stumbled on something. I bought an X5 E70 with the "Poor Pack" crap sound system and bought a second hand Harman/Kardon kit on eBay for $300.
I fitted it myself and 'blackjacked' the under seat sub enclosures and added damping foam and drove them with a Harman/ Infinity 'D' amp with the LPF set at 32Kz to 320Hz. The subs still sounded pretty bad and I read everything on here. I have no clue what the crossover point in the standard system is, to the subs, but everyone says they are not really subs. I adjusted the amp LPF at 32Hz to about somewhere between 150Hz and 200Hz. The difference is just astonishing. The H/K subs are now behaving like subs with a sharp, rich, solid Bass. I still may upgrade them but they are quite listenable right now. I suggest anyone not happy with the subs (everyone) try crossing them differently with the LPF adjustment on their amplifier.